"""
    全局变量
"""
if __name__ == '__main__':
    print(__name__)  # >>> __main__
    print("当前文件自身执行, 外部调用不会执行")

author = "lizmein"
desc = "基本加减乘除方法"
def add(a, b):
    return a + b
def sub(a, b):
    return a - b
def mul(a, b):
    return a * b
def div(a, b):
    return a / b
